This are actually two bugs:

T1:

• Load image + create segmentation
• Use e.g. threshold and confirm + tell MITK to create a new segmentation
• New segmentation is not selected in the combo box!
• Delete the new segmentation -> tools are disabled although there is still a valid segmentation in the data manager.

T2:

• Now select a segmentation via combo box
• change its visibility
• e.g. the threshold slider are not initialized correctly
• using the two threshold leads to a crash